Dual-emission carbon dots-stabilized copper nanoclusters for ratiometric and visual detection of Cr2O72- ions and Cd2+ ions.

The pollution of heavy metal increases greatly accompanying by the development of industries. So, it is very important to build up a quick and reliable technique for detection of heavy metal ions. In this work, we developed a simple and convenient method for ratiometric and visual detection of Cr2O72- ions and Cd2+ ions. We utilized glutathione as raw material to prepare cyan-emitting carbon dots (GSH@CDs). The GSH@CDs were further used as the template to prepare carbon dots-stabilized copper nanoclusters (GSH@CDs-Cu NCs) that displayed two well-separated emission peaks respectively at 450 nm and 750 nm. The GSH@CDs-Cu NCs can be applied for the ratiometric and visual detection of Cr2O72- and Cd2+ ions based on the fluorescence quenching or enhancement of GSH@CDs-Cu NCs at 750 nm. A linear range of 2-40 µmol L-1 with a detection limit of 0.9 µmol L-1 for Cr2O72- ions, and a linear range of 0-20 µmol L-1 with a detection limit of 0.6 µmol L-1 for Cd2+ ions were achieved based on this method. The fluorescent test strips for Cr2O72- ions were successfully prepared based on GSH@CDs-Cu NCs. Moreover, the GSH@CDs-Cu NCs were successfully applied to determine Cr2O72- and Cd2+ ions in real samples with promising results.